Originally Posted by thrasherht
you don't understand. think about it this way, if you have a car that is being over revved because of less restriction on it. it is working less, but destroying itself because it is going to fast.
when the pump is spinning too fast, the electronics have to work harder to keep up with the rotations. which heats them up.
swiftech built that pump with a certain level of restriction in mind, by changing the pump top, you are also changing that restriction, so in theory i could make the pump go faster then designed.
What you just described isn't mechanically possible with the way this pump is designed or constructed. The rotor and the drive mechanism aren't mechanically linked; it's magnetically linked using an electronically controlled electromagnet.
Originally Posted by Laing's documentation
How the DDC Pump Works:
The permanent magnet rotor/impeller unit is driven by the magnetic field generated by the surrounding stator. The stator is wrapped entirely around the rotor. As a result, the entire pump is only slightly taller than the rotor itself, measuring only 1.5‘‘ in height, perfect for applications where space is limited.
The pump can't sense the rotation speed of the impeller on the 355 either; it's set to a constant speed, so for all it cares the impeller could be spinning at 20k RPM a second. The electromagnet turning the impeller would still "turn" at XYZ speed.
What you're not understanding here is that the pump lacks a mechanical commutator and a mechanical connection to the impeller, and there's no outside force pushing the rotor past a certain speed. If what you're trying to describe was true then res tops would be the least of everyone's concern; anyone with a multi-pump setup would be having their secondary pumps burn out. The primary pump would be effectively removing the intake restriction on the second pump and causing this issue.
As we all know, nobody with a dual pump setup has been experiencing this issue (that we know of).
Your car analogy is flawed too BTW.
I can't say all cars have this, but I know my car for certain has it..
I've got a 2002 Acura RSX (Type S) w/a six speed manual transmission. The car redlines from 8000RPM to 9000RPM. If you try to exceed 9000RPM though, the rev limiter kicks in and prevents you from doing so. It doesn't matter if the wheels are off of the ground or on the pavement, the rev limiter in the ECU kicks in and prevents the engine from exceeding max RPM.
Now.. say I was driving @70MPH while in sixth gear and decided to pull a stupid and drop it into 2nd gear. Sure the synchros in the tranny are supposed to prevent me from doing that, but if you force it, it'll go. At that point the rev limiter won't do jack since I've got an outside force (the forward momentum of the car) acting on the engine to go past max redline. The engine won't be contributing to the forward momentum at this point; if anything it'll be acting as a brake and slowing down the car. Heck, at those speeds though it'd be lucky if I didn't leave some necessary engine parts behind me on the road.
In the case of a mag drive pump, if the impeller tried spinning faster than the magnetic field that the stator is generating, the impeller would then get held back by that magnetic field (acting as a brake). If the impeller somehow managed to spin faster than the magnetic field's rotation in the stator though; the worst that would happen would be that the impeller would "jump" to the next field. If you somehow managed to get the impeller spinning REALLY fast by using another pump, I could potentially see the pump turning into a generator of sorts and causing a power back-flow into the pump's electronics. By itself though, no replacement top is capable of causing that.
All the same it's a bad analogy to a mag drive pump though since a car has a mechanical engine with a mechanical link to the wheels (a clutch or torque converter and transmission). That and you're adding the external force of the car's forward momentum.
But I digress.
With all due respect, Swiftech also did not design or build these pumps, Laing did. If there was really a problem with res tops on the 355/DDC pumps, we'd be hearing about this from people who've bought these pumps directly from Laing or from Danger Den too.
If the problem was the impeller was getting damaged or something along those lines I'd be more inclined to believe it.
The excuse that a res top is causing the pump to burn out because of a lack of restriction, when even pumps that don't have a replacement top are also burning out? Sorry, I don't buy it. It smells like a red herring.
Chunky_Chimp: would you be able to contact someone at Laing to get a definitive answer? If anyone would be able to get to the bottom of this, I believe they could since they make the pumps for Swiftech.Edited by Digidoc - 1/13/11 at 8:58am